<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="js/vue.js"></script>
    <style>
        #app {
            width: 600px;
            margin: 40px auto;
            text-align: center;
        }
    </style>
</head>

<body>
    <div id="app">
        <h2>当前计数器的值为：{{num}}</h2>
        <counter v-on:counter-add="num++"></counter>
    </div>

    <script>
        Vue.component('counter', {
            template: `<button @click="add">计数器</button>`,
            methods: {
                add: function () {
                    this.$emit('counter-add')
                }
            }
        })
    </script>
    
    <script>
        let app = new Vue({
            el: "#app",
            data: {
                num: 0
            },
            methods: {
                handleAdd: function () {
                    this.num++
                }
            }
        })
    </script>
</body>

</html>